**** HOW I PHOTOGRAPH ***
*** MY EPIPHYTIC CACTI ***
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SOME TECHNICAL POINTS
OF PHOTOGRAPHY
(Doc P.Gori - Public domain from "Parlons Photo": http://www.parlonsphoto.com/ )
Sensor > sensitivity
Diaphragm > aperture
Shutter > exposure time
The diaphragm is the equivalent of the pupil of the eye. It is open wide to let much light enter or open narrow to let less light pass (and to improve the depth of field).
My macro lens opens F/ 2.8 (maximum opening) to F/ 32 (minimal opening).
The shutter opens to let the light pass to the sensor during exposure and is closed when the adequate quantity of light has been collected by the sensor. The opening time of the shutter is called exposure time or wrongly shutter speed. An exposure time of 1/60s for example means that the shutter remained open during 1/60 of second to take the picture. A short exposure time avoids the blurs due to the movements of the camera.
The sensor is the equivalent of the old photographic film. It's on the sensor that the image of the photographed object is formed, image which is then recorded. The sensitivity of the sensor is adjustable. Formerly there were films of several sensitivities but as soon as the film started, the sensitivity was fixed for all the film. With a digital sensor, the sensitivity of the sensor can be changed for each photograph (which is usually not done).
To let a certain quantity of light enter, it will be necessary to choose a short exposure time with a wide open diaphragm or a longer exposure time with a diaphragm more closed.
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